1. Field of the Invention
The present invention relates to an antenna, and more particularly to a coupling antenna increasing the operating bandwidth thereof.
2. Description of Related Art
Wireless telecommunication technologies have greatly developed to be mature, reliable and marketable so that the market demand for the wireless products greatly increases in the recent years. Antennas, the most important components in wireless products, are designed to increase the operating bandwidth and reduced the size thereof to make the wireless products have high performance and compact structure.
The telecommunication protocols in different areas are distinct and employ different bandwidths. Therefore, wireless product manufacturers design the wireless products to have modulating functions.
With reference to FIG. 1, a conventional multi-band antenna (100) comprises a ground plane (GPN), a pair of regulators (REG), a shorting member (ST) and a first radiating member (110), a second radiating member (150) and a third radiating member (170). The ground plane (GPN) has two ends and a grounding member (G). The regulators (REG) are mounted respectively on the ends of the ground plane (GPN). The shorting member (ST) is formed on the ground plane (GPN) and forms a short circuit between the radiating members (110, 150, 170) and the ground plane (GPN) to reduce the size of the antenna (100). The first radiating member (110) protrudes from the shorting member (ST) and is used to adjust a low operating bandwidth. The second radiating member (150) is connected perpendicularly to the shorting member (ST) and the first radiating member (110) and is used to adjust a low frequency characteristic of a high operating bandwidth. The third radiating member (170) protrudes from the second radiating member (150) and is used to adjust a high frequency characteristic of the high operating bandwidth.
However, the complicated structure of the second and third radiating members (150, 170) greatly increases the thickness of the whole antenna. Furthermore, the antenna (100) is formed by stamping processes. However, the regulators (REG), grounding member (G), shorting circuit member (ST) on the ground plane (GPN) is too tiny to be stamped so that the production rate of the antenna is low. Moreover, the regulators (REG) on the ground plane (GPN) further complicate the structure of the antenna and limit the operating bandwidth of the antenna.
To overcome the shortcomings, the present invention provides a coupling antenna to mitigate or obviate the aforementioned problems.